Cutis verticis gyrata is a medical condition usually associated with thickening of the scalp. People show visible folds, ridges or creases on the surface of the top of the scalp. The number of folds can vary from two to roughly ten and are typically soft and spongy. These folds cannot be corrected with pressure. The condition typically affects the central and rear regions of the scalp, but sometimes can involve the entire scalp."

Source : Wikipedia

The cause of CVG is unknown. In most cases, genetic factors are not regarded as a factor. The only treatment currently available proven treatment is plastic surgery - though the condition is generally regarded as benign.(ref.)